Fuel injection nozzle with hydraulic valve-closing means

ABSTRACT

A fuel injection system having a nozzle with a differential valve normally biased to a closed position by means of a spring with augmentation of hydraulic means. The hydraulic means include a source of pressurized fluid with pressure-regulating means to provide a fluid pressure biasing the differential valve to a closed position.

nite States Patent Inventor Alexander Dreisin Olympia Fields, Ill.

App]. No. 884,491

Filed Dec. 12,1969

Patented Dec. 7, 1971 Assignee Allis-Chalmers Manufacturing Company Milwaukee, Wis.

FUEL INJECTION NOZZLE WITH HYDRAULIC VALVE-CLOSING MEANS 10 Claims, 2 Drawing Figs.

US. Cl 123/ 139, 123/139 AT Int. Cl ..F02m 47/02 Field of Search 123/139,

139 AL, 139 AN, 139 AT, 140

[56] References Cited UNITED STATES PATENTS 2,150,574 3/1939 Amery 123/139.15 2,191,186 2/1940 Amery l23/l39.15 2,274,315 2/1942 Amery 123/139 X 2,291,939 8/1942 Amery..... 123/139 2,323,184 6/1943 Amery l23/l39.15

Primary Examiner- Laurence M. Goodridge AuorneysArthur L. Nelson, Charles L. Schwab and Robert B. Benson ABSTRACT: A fuel injection system having a nozzle with a differential valve normally biased to a closed position by means of a spring with augmentation of hydraulic means. The hydraulic means include a source of pressurized fluid with pressure-regulating means to provide a fluid pressure biasing the differential valve to a closed position.

SPEED AND LOAD RESPONSIVE DEVICE FUEL INJECTION PUMP PATENTEDDEC 7191: 3.625192 sum 1 OF 2 FUEL.

INJECTION PUMP SPEED AND LOAD RESPONSIVE DEVICE ENGINE PATENTEDUEB Hen 3.625192 SHEET 2 OF 2 FUEL SUPPLY FUEL INJECTION NOZZLE WITll-I HYDRAULIC VALVE- ClLOSING MEANS This invention relates to a fuel injection nozzle for an internal combustion engine and more particularly to a spring with hydraulic means normally biasing the differential valve to a closed position. The pressure in the hydraulic system is controlled with the speed of the engine and permits low differential valve-opening pressures for low speeds and increases to higher pressures under higher engine speed and load conditions.

The current practice used in conjunction with closing differential valves in fuel injection nozzles is to employ a coil spring which acts on the nozzle differential valve to normally close the valve. The opening pressure of the nozzle gradually decreases during the life of the nozzle due to wear of the spring ends, wear of the abutting parts, and wear of the nozzle valve seat. This gradually leads to deterioration in noule function. Nozzle-closing pressure is a constant fraction of the nozzle-opening pressure and should be higher than peak cylinder pressures developed by the combustion gases. This requirement is dictated by the fact that otherwise combustion gases enter the inside of the nozzle at the end of injection, prevent quick closing of the nozzle valve, and cause carboning of the internal nozzle parts, As the level of the engine turbocharging increases, so do the peak cylinder pressures, forcing the engine designer to raise opening pressures of the nozzles. This circumstance, in turn, increases the rate of opening pressure loss.

In addition, high nozzle-opening pressures present an additional handicap from the standpoint of engine starting. At starting, when the engine speeds are low and during the cranking cycle, injection pump losses due to leakage are considerable. High nozzle-opening pressures increase the leakage loss. In practice, with high nozzle-opening pressures, it may be difficult to maintain the rate of injection high enough to obtain satisfactory engine starting.

Accordingly this invention would allow low valve-opening pressure for engine starting and would raise the opening pressure to the required values at high engine speeds and loads. In addition it will maintain the desired opening pressure at a constant level indefinitely and independent of the amount of wear of the noule seat and other parts.

This invention employs a weak spring which develops only enough force for low opening pressure during the starting cycle. The space above the differential valve is connected to a source of hydraulic pressure and is filled with fuel oil. A common hydraulic line is connected to all of the nozzles. On the inlet end of this line a nonreturnable valve is arranged and on the outlet end a pressure relief valve, which maintains a hydraulic pressure in the common hydraulic line at a desired value. The downstream side of the relief valve is connected by a drain line to the fuel tank. The upstream side of the nonreturnable valve receives hydraulic pressure either from an auxiliary pump or from a bleed orifice which is arranged in the hydraulic head of the distributor-type injection pump. An alternate solution would be to obtain the hydraulic pressure from the bleed orifice arranged in the delivery union of one of the pumping elements of an inline-type injection pump. The sizes of the bleed orifice would be made small enough so that the flow of fuel oil into the common line would be very small compared with the quantities injected normally into the nozzles and therefore would not affect appreciably the normal functioning of the fuel injection pump. Opening pressure of the nonreturnable valve is adjusted to a valve which is higher than the nozzle opening pressure required for engine starting.

It is an object of this invention to provide a fuel injection nozzle having a differential valve of low opening pressure for engine starting and means for raising the opening pressure to a higher value at higher engine speeds and loads.

It is another object of this invention to provide a fuel injection nozzle having a differential valve wherein the operating level for the opening pressure of the differential valve is maintained constant indefinitely and independent of the amount of wear of the nozzle spring and other related parts.

It is a further object of this invention to provide hydraulic means augmenting a spring for maintaining a constant closing force on the differential valve.

It is a further object of this invention to provide a lightweight spring to normally close the differential valve of a fuel injection nozzle and having a hydraulic system with a commonrail supplying pressurized fluid to maintain a constant closing force for the differential valve at normal operating speeds and loads.

The objects of this invention are accomplished providing a source of pressurized fluid and means for regulating the pressure at a relatively constant value. The pressure may vary with the speed of the engine and preferably for low engine speeds and cranking speeds the pressure will be substantially lower to improve fuel injection operating characteristics. The pressurized fluid in the hydraulic system is connected through a common hydraulic line to all of the fuel injectors on the engine. Hydraulic fluid operates a piston to augment the closing force of a coil spring in the fuel injector to normally close the differential valve. The pressurized fluid augmenting the closing of the differential valve provides a means of operating with a uniform closing force on the differential valve which is not affected by wear of the spring components which normally biases the differential valve to a closed position. The system ordinarily operates with low opening pressures of the differential valve and increases the operating pressures to a normally constant differential valve opening pressure for higher speeds and loads when the pressure of the combustion gases in the combustion chamber normally are much higher.

Referring to the drawings the preferred embodiments of this invention are illustrated.

FIG. 1 illustrates a schematic diagram of the fuel injection system and the auxiliary system with a fuel injection nozzle in cross section; and

FIG. 2 illustrates a modification of the fuel injection nozzle wherein the fuel pump drive in a manner shown in H6. I operates as a single source of pressurized fluid wherein a bleed passage is used to bleed ofl pressurized fluid to the common hydraulic line supplying hydraulic fluid to augment closing of the difierential valve.

Referring to the drawing, FIG. I illustrates an engine 1 operating a speed and load responsive device 2 which in turn drives the fuel injection pump 3. The auxiliary pump 4 may be driven through the speed responsive device 2 as shown. Driving the auxiliary pump 4 through the speed and load responsive device will provide increasing pressures with an increasing speed of the engine and will give the advantage of low closing pressures for the differential valve at cranking speeds and higher closing pressures when the engine is operating at higher speeds.

The fuel injection pump 3 supplies pressurized fluid to the inlet passage 5 for fuel injection by nozzle 6 and to each of the other injection nozzles 7, 8 and 9 as shown. The fuel injection nozzles are suitably mounted on the engine 1 and provide injection in the proper sequence and timing for operation of the engine.

The fuel injection nozzle 6 is illustrated with a housing 10 defining a cylindrical opening 11 receiving the needle 12 of the differential valve 13. The needle 12 of the differential valve 13 is biased to a closed position by the spring I4. The chamber 15 is in communication with the common hydraulic line 17 of the auxiliary hydraulic system 18. The differential valve I3 operates to control the flow of pressurized fluid from the chamber 19 in the nozzle tip 20. The orifices 2I spray fuel into the combustion chamber when the differential valve 13 is open.

Auxiliary pump 4 is part of the auxiliary hydraulic system 18 augmenting the force of spring 14 for closing the difierential valve 13. The system also includes a nonreturnable valve 22 normally biased to a closed position and permitting pressurized fluid to flow into the common line 17 when a predetermined pressure from the auxiliary pump is reached. The pressurized fluid in the system is maintained at a predetermined pressure by the relief valve 23. The relief valve 23 permits return flow of pressurized fluid from the common line 17 to the fuel supply 24 and maintains a predetermined pressure level in the auxiliary system 18. The conduit 25 is in communication with the line 17 as well as the conduits 26, 27, 28 which lead to their respective injection nozzles 6, 7, 8 and 9.

The basic function of the auxiliary hydraulic system 18 is to maintain a predetermined operating pressure in the system which will augment closing of the differential valve in response to the pressure of the system and the area of the plunger 30 on the end of the needle 12 of the differential valve.

FIG. 2 illustrates a modification of the system wherein the fuel injection nozzle 31 includes a difierential valve 32. The fuel injection pump 33 pressurizes fluid which is in communication with the chamber 34 of nozzle 31 through conduit 35, Pressurized fluid opens the differential valve 32 for discharge from the nozzle.

The pressurized fluid from the fuel injection pump 33 is used to produce pressure in an auxiliary pressure system including the common line 36 by means of the bleed passage 37 in communication with the high-pressure chamber 50. Bleeding of pressurized fluid to the line 36 produces a pressure in the line 46 of a predetermined value which is set by the relief valve 40. The relief valve 40 permits the return of flow of pressurized fluid to the fuel supply 41. The relief valve maintains a predetermined pressure in the chamber 45 which augments the spring 43 in closing ofthe differential valve 32.

The operation of the fuel injection system will be subsequently described.

At engine starting, the spring force of spring 14 which provides a low value of nozzle opening pressure, for example, l,000 p.s.i., together with the force of any residual pressure in the system 18 closes the differential valve. When the starter begins to crank the engine the injection pump 3 will pump fuel to the nozzle in a conventional manner. Injection pressure will be limited by the nozzle opening pressure. At this point, the fuel trapped in the auxiliary system will be essentially at ambient pressure. After starting, as the engine speed goes up, the injection pressure will be governed by the area of the nozzle orifices.

Referring to FIG. 2, when the injection pump pressure reaches the opening pressure of the nonretumable valve 60, a small portion of the fuel will flow through the bleed passage 37 in the injection pump and will open the nonretumable valve 60 to flow into a common hydraulic line 36 which is communication with all the fuel injection nozzles. The quantity of flow into the common line will be determined by the size of the bleed hole 37 and the opening pressure of the nonretumable valve 60 and the pressure relief valve 40. Pressure in the common line 36 will be determined by the opening pressure of the relief valve 40. Valve 40 may be adjusted, for example, to an average of 2,000 p.s.i. Assuming the differential valve has a seat diameter which is one-half of the diameter of its guided portion, in that case the opening pressure of the nozzle will be 2,000 times four-thirds which equals 2,700 p.s.i. plus 1,000 p.s.i. due to the spring force which would equal 3,700 p.s.i. When the differential valve 32 opens, pressurized fluid is injected through the orifice 61 and to the combustion chamber of the engine. The fuel injection continues so long as the fuel injection pump supplies hih-pressure fluid to the inlet passage 39 in fuel injection nozzle 31. Fuel injection is terminated when the fuel pressure from the injection pump drops below a predetermined pressure. At this point, fuel injection is terminated and the spring pressure and fluid pressure in chamber 45 close the difl'erential valve with a crisp positive closing action.

Referring to the operation of the hydraulic system as shown in HO. 1, the auxiliary pump as well as the fuel injection pump, is driven by a speed and load responsive device. When fuel injection is terminated, the pressure in the system 18 augments the closing of the differential valve 13 together with the spring 14.

The hydraulic system 18 and the connecting passages 25. 26, 27 and 28 to the fuel injection nozzle 6, 7, 8 and 9 among other functions serve the function of low-pressure drain passages in a conventional system. The auxiliary pump 4 and valves 22 and 23 however, pressurize the system, and a fuel return line 65 returns fuel to the fuel supply. The system as shown provides for a second source of pressurized fluid supplying the pressure which augments the closing of the differential valve.

The preferred embodiments of this invention have been illustrated and described.

The embodiments of the invention in which an exclusive property or privilege is claimed and defined as follows:

1. A fuel injection system for an internal combustion engine comprising a fuel injection pump on an internal combustion engine, an auxiliary source of pressurized fluid, a fuel injection nozzle including a differential valve, said differential valve defining a high-pressure fuel injection chamber with said differential valve opening in response to high-pressure fuel in said high-pressure chamber conduit means connecting said fuel injection pump with said high-pressure fuel injection chamber of said differential valve for supplying high-pressure fuel thereto and to said engine and controlling the opening of said differential valve, a plunger means defining a needle of said differential valve, said plunger means reciprocally mounted in said nozzle defining a variable volume fluid chamber, a spring in said fluid chamber normally biasing said dilferential valve to a closed position, conduit means connecting said source of pressurized fluid to said variable volume fluid chamber for continuously supplying pressurized fluid from said source of pressurized fluid to said variable volume fluid chamber of said nozzle, said differential valve thereby opening in response to high-pressure fuel from said fuel injection pump and closing in response to the biasing force of said spring and the augmenting force of the pressurized fluid in said variable volume fluid chamber.

2. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid includes an auxiliary pump in an auxiliary system connected to said fluid chamber.

3. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid includes an auxiliary fluid system comprising, an auxiliary pump, relief valve means for maintaining a predetermined pressure level in said auxiliary system.

4. A fuel injection system for an internal combustion engine as set forth in claim 1 including an auxiliary fluid system comprising, an auxiliary fluid pump, a fluid supply supplying fluid to said auxiliary pump, a nonretumable valve connected to the discharge side of said auxiliary pump, a relief valve maintaining a predetermined pressure level in said auxiliary system and returning pressurized fluid to said supply.

5. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid comprises an auxiliary fluid system including a relief valve for maintaining a predetermined pressure level in said auxiliary system, a bleed passage connected between said fuel injection pump and said auxiliary system to supply pressurized fluid from said fuel injection pump and to thereby produce a predetermined operating pressure in said auxiliary system.

6. A fuel injection system for an internal combustion engine as set forth in claim 2 including means on said engine driving said auxiliary pump, said spring effectively providing the biasing means biasing said differential valve to a closed position at cranking speed.

7. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid includes an auxiliary fluid system comprising a common line transmitting hydraulic fluid, a plurality of fuel injection nozzles, conduit means connecting the variable volume chamber of each of said plurality fuel injection nozzles to said common line, an auxiliary pump having a fluid supply, a unidirectional valve permitting the flow of pressurized fuel from said pump to said line, a relief valve connected between said line and the fuel supply for maintaining a predetermined pressure in said line and permitting the return flow of pressurized fluid to the fluid supply.

8. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid includes an auxiliary fluid system comprising, a constant pressure conduit connected to the fluid chamber of at least one fuel injection nozzle, said fuel injection pump defining a bleed passage bleeding pressurized fuel from the pumping chamber of said injection pump to said constant pressure conduit, a pressure relief valve for maintaining a predetermined pressure 

1. A fuel injection system for an internal combustion engine comprising, a fuel injection pump on an internal combustion engine, an auxiliary source of pressurized fluid, a fuel injection nozzle including a differential valve, said differential valve defining a high-pressure fuel injection chamber with said differential valve opening in response to highpressure fuel in said high-pressure chamber, conduit means connecting said fuel injection pump with said high-pressure fuel injection chamber of said differential valve for supplying highpressure fuel thereto and to said engine and controlling the opening of said differential valve, a plunger means defining a needle of said differential valve, said plunger means reciprocally mounted in said nozzle defining a variable volume fluid chamber, a spring in said fluid chamber normally biasing said differential valve to a closed position, conduit means connecting said source of pressurized fluid to said variable volume fluid chamber for continuously supplying pressurized fluid from said source of pressurized fluid to said variable volume fluid chamber of said nozzle, said differential valve thereby opening in response to high-pressure fuel from said fuel injection pump and closing in response to the biasing force of said spring and the augmenting force of the pressurized fluid in said variable volume fluid chamber.
 2. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid includes an auxiliary pump in an auxiliary system connected to said fluid chamber.
 3. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid incLudes an auxiliary fluid system comprising, an auxiliary pump, relief valve means for maintaining a predetermined pressure level in said auxiliary system.
 4. A fuel injection system for an internal combustion engine as set forth in claim 1 including an auxiliary fluid system comprising, an auxiliary fluid pump, a fluid supply supplying fluid to said auxiliary pump, a nonreturnable valve connected to the discharge side of said auxiliary pump, a relief valve maintaining a predetermined pressure level in said auxiliary system and returning pressurized fluid to said supply.
 5. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid comprises an auxiliary fluid system including a relief valve for maintaining a predetermined pressure level in said auxiliary system, a bleed passage connected between said fuel injection pump and said auxiliary system to supply pressurized fluid from said fuel injection pump and to thereby produce a predetermined operating pressure in said auxiliary system.
 6. A fuel injection system for an internal combustion engine as set forth in claim 2 including means on said engine driving said auxiliary pump, said spring effectively providing the biasing means biasing said differential valve to a closed position at cranking speed.
 7. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid includes an auxiliary fluid system comprising a common line transmitting hydraulic fluid, a plurality of fuel injection nozzles, conduit means connecting the variable volume chamber of each of said plurality fuel injection nozzles to said common line, an auxiliary pump having a fluid supply, a unidirectional valve permitting the flow of pressurized fuel from said pump to said line, a relief valve connected between said line and the fuel supply for maintaining a predetermined pressure in said line and permitting the return flow of pressurized fluid to the fluid supply.
 8. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said source of pressurized fluid includes an auxiliary fluid system comprising, a constant pressure conduit connected to the fluid chamber of at least one fuel injection nozzle, said fuel injection pump defining a bleed passage bleeding pressurized fuel from the pumping chamber of said injection pump to said constant pressure conduit, a pressure relief valve for maintaining a predetermined pressure level in said auxiliary system.
 9. A fuel injection system for an internal combustion engine as set forth in claim 3 wherein said relief valve includes means to very the pressure level.
 10. A fuel injection system for an internal combustion engine as set forth in claim 1 wherein said needle of said differential valve in said fuel injector is integral with said plunger means and defines said variable volume chamber receiving said spring normally biasing said differential valve to a closed position. 